Product Design Craft

Transform interfaces from "works correctly" to "feels like a funded startup built this." This skill encodes the design DNA of elite products: Linear, Stripe, Superhuman, Figma, Notion, and Slack.

Design DNA: What Elite Products Share

Linear: Surgical Precision

• Density without clutter: Information-rich screens that remain scannable
• Keyboard-first: Command palette (⌘K), shortcuts visible on hover
• Monochromatic confidence: Limited palette, relies on spacing and typography hierarchy
• Speed as feature: Optimistic updates, instant feedback, no loading spinners for fast operations

Stripe: Trust Through Clarity

• Progressive disclosure: Complexity revealed gradually, not dumped
• Gradient mastery: Subtle, purposeful gradients that add depth without distraction
• Documentation-grade copywriting: Every label teaches, every error helps
• Generous whitespace: Breathing room signals confidence

Superhuman: Feels Instant

• Split-pane mental model: Consistent spatial relationships
• Aggressive prefetching: UI ready before user commits to action
• Keyboard velocity: Every action has a shortcut, shortcuts are discoverable
• Reduced motion that still communicates: Transitions under 150ms

Figma: Multiplayer Awareness

• Presence indicators: Always know who's where
• Contextual tooling: Right tools appear at right moment
• Canvas confidence: Infinite space, zoom as navigation
• Collaborative cursors: Others' actions visible in real-time

Notion: Calm Flexibility

• Block-based composition: Everything is moveable, nestable
• Slash commands: Power hidden behind simple gesture
• Typographic hierarchy: Headers, toggles, callouts—structure through type
• Empty states that invite: Never feel lost, always know next action

Slack: Conversational Flow

• Threading without confusion: Clear parent-child relationships
• Presence as interface: Online status, typing indicators
• Emoji as UI: Reactions reduce noise, add signal
• Channel patterns: Consistent navigation, predictable information architecture

Foundation Systems

Typography Scale

Never use default type scales. Create intentional hierarchy:

/* Recommended scale: 1.2 ratio (minor third) */
--text-xs: 0.694rem;    /* 11px - metadata, timestamps */
--text-sm: 0.833rem;    /* 13px - secondary content */
--text-base: 1rem;      /* 16px - body text */
--text-lg: 1.2rem;      /* 19px - subheadings */
--text-xl: 1.44rem;     /* 23px - section headers */
--text-2xl: 1.728rem;   /* 28px - page titles */
--text-3xl: 2.074rem;   /* 33px - hero text */

/* Line heights tighten as size increases */
--leading-tight: 1.25;   /* headings */
--leading-snug: 1.375;   /* subheadings */
--leading-normal: 1.5;   /* body */
--leading-relaxed: 1.625; /* small text */

Font pairing strategy:

• Display/headings: One distinctive font (Söhne, Untitled Sans, GT America, Satoshi, General Sans, Cabinet Grotesk)
• Body/UI: One highly legible font (often the same family's regular weight, or a complementary geometric sans)
• Mono: For code, data, timestamps (JetBrains Mono, Berkeley Mono, Fira Code, IBM Plex Mono)

Color System Architecture

Build semantic, not static palettes:

/* Foundation: Neutral scale (10 steps minimum) */
--gray-50 through --gray-950

/* Semantic tokens - the actual interface */
--color-bg-primary: var(--gray-50);
--color-bg-secondary: var(--gray-100);
--color-bg-tertiary: var(--gray-200);
--color-bg-inverse: var(--gray-900);

--color-text-primary: var(--gray-900);
--color-text-secondary: var(--gray-600);
--color-text-tertiary: var(--gray-500);
--color-text-inverse: var(--gray-50);

--color-border-default: var(--gray-200);
--color-border-strong: var(--gray-300);
--color-border-focus: var(--brand-500);

/* Brand: Primary action color */
--brand-50 through --brand-950

/* Status colors: Each needs full scale for backgrounds, text, borders */
--success-*, --warning-*, --error-*, --info-*

Dark mode strategy: Don't just invert. Dark backgrounds should be warm grays (not pure black), text should be slightly off-white (not #fff), and colors need different saturation levels.

Spacing Rhythm

Use a base-4 or base-8 system consistently:

/* Base-4 system */
--space-1: 0.25rem;  /* 4px - tight internal */
--space-2: 0.5rem;   /* 8px - default internal */
--space-3: 0.75rem;  /* 12px - comfortable internal */
--space-4: 1rem;     /* 16px - component padding */
--space-6: 1.5rem;   /* 24px - section spacing */
--space-8: 2rem;     /* 32px - group separation */
--space-12: 3rem;    /* 48px - major sections */
--space-16: 4rem;    /* 64px - page-level breaks */

Component Craftsmanship

Every Component Needs These States

1. Default: Base appearance
2. Hover: Subtle feedback (opacity, background shift, border change)
3. Focus: Visible ring (accessibility requirement), distinct from hover
4. Active/Pressed: Slight scale down or color shift
5. Disabled: Reduced opacity + cursor change + no pointer events
6. Loading: Spinner or skeleton, never blank

Interaction State Principles

/* Hover: Subtle, immediate */
.button:hover {
  background: var(--color-bg-hover);
  transition: background 100ms ease-out;
}

/* Focus: Visible, accessible */
.button:focus-visible {
  outline: 2px solid var(--color-border-focus);
  outline-offset: 2px;
}

/* Active: Tactile feedback */
.button:active {
  transform: scale(0.98);
  transition: transform 50ms ease-out;
}

/* Disabled: Clearly non-interactive */
.button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

shadcn/ui Customization Guide

shadcn provides excellent foundations. The craft is in customization:

1. Override the default theme in globals.css:

@layer base {
  :root {
    /* Replace default slate with your gray scale */
    --background: 0 0% 98%;        /* Warm off-white, not pure white */
    --foreground: 240 10% 10%;     /* Slightly warm black */

    /* Custom radius - smaller feels more refined */
    --radius: 0.375rem;            /* 6px instead of default 8px */

    /* Custom primary that's not blue */
    --primary: 262 83% 58%;        /* Purple example */
    --primary-foreground: 0 0% 100%;
  }

  .dark {
    --background: 240 10% 8%;      /* Warm dark, not pure black */
    --foreground: 0 0% 95%;        /* Off-white, not pure white */
  }
}

2. Extend component variants in your component files:

// Add custom variants beyond default/destructive/outline
const buttonVariants = cva(
  "inline-flex items-center justify-center...",
  {
    variants: {
      variant: {
        default: "...",
        // Add: subtle variant for secondary actions
        subtle: "bg-secondary/50 text-secondary-foreground hover:bg-secondary/80",
        // Add: ghost with colored hover
        "ghost-primary": "hover:bg-primary/10 hover:text-primary",
      },
      size: {
        default: "h-9 px-4 py-2",
        // Add: compact for dense UIs
        compact: "h-7 px-2 text-xs",
      }
    }
  }
)

3. Add motion to shadcn components:

// Wrap Dialog content with motion
<Dialog>
  <DialogContent asChild>
    <motion.div
      initial={{ opacity: 0, scale: 0.95, y: 10 }}
      animate={{ opacity: 1, scale: 1, y: 0 }}
      exit={{ opacity: 0, scale: 0.95, y: 10 }}
      transition={{ duration: 0.15, ease: "easeOut" }}
    >
      {/* content */}
    </motion.div>
  </DialogContent>
</Dialog>

4. Custom focus rings (replace default):

@layer base {
  /* Remove default focus, add custom */
  *:focus {
    outline: none;
  }

  *:focus-visible {
    outline: 2px solid hsl(var(--ring));
    outline-offset: 2px;
    border-radius: calc(var(--radius) + 2px);
  }
}

Motion Principles

Timing Guidelines

CSS Motion Defaults

/* Utility classes for common transitions */
.transition-fast { transition: all 100ms ease-out; }
.transition-base { transition: all 150ms ease-out; }
.transition-slow { transition: all 250ms ease-out; }

/* Entrance animations */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes scaleIn {
  from { opacity: 0; transform: scale(0.95); }
  to { opacity: 1; transform: scale(1); }
}

/* Apply with stagger */
.stagger-item {
  animation: slideUp 200ms ease-out backwards;
}
.stagger-item:nth-child(1) { animation-delay: 0ms; }
.stagger-item:nth-child(2) { animation-delay: 30ms; }
.stagger-item:nth-child(3) { animation-delay: 60ms; }
/* ... */

Reduced Motion Support

Always provide reduced motion alternatives:

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

Edge Cases: First-Class Citizens

Empty States

Never show blank space. Every empty state needs:

1. Visual: Illustration or icon (not generic)
2. Headline: What this area is for
3. Description: Why it's empty or what to do
4. CTA: Clear next action

┌─────────────────────────────────────┐
│                                     │
│           [Illustration]            │
│                                     │
│         No projects yet             │
│                                     │
│   Projects help you organize work   │
│   into focused collections.         │
│                                     │
│        [+ Create project]           │
│                                     │
└─────────────────────────────────────┘

Loading States

Match the content shape (skeleton screens):

.skeleton {
  background: linear-gradient(
    90deg,
    var(--gray-200) 0%,
    var(--gray-100) 50%,
    var(--gray-200) 100%
  );
  background-size: 200% 100%;
  animation: skeleton-shimmer 1.5s ease-in-out infinite;
  border-radius: var(--radius);
}

@keyframes skeleton-shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

Error States

Errors should help, not blame:

• Inline validation: Show errors adjacent to the field, not in alerts
• Specific messages: "Email must include @" not "Invalid input"
• Recovery path: Tell users exactly how to fix it
• Persistent until fixed: Don't auto-dismiss error states

Optimistic Updates

For fast-feeling UIs:

1. Update UI immediately on user action
2. Send request to server in background
3. If fails, revert UI and show non-blocking error
4. If succeeds, optionally confirm (subtle toast or no feedback needed)

Keyboard & Accessibility

Focus Management

• Tab order must be logical (DOM order matters)
• Focus trap in modals (can't tab out until closed)
• Return focus to trigger element when modal closes
• Skip links for main content

Keyboard Shortcuts

For power user tools:

• Show shortcuts in tooltips: "Copy (⌘C)"
• Implement command palette (⌘K pattern)
• Support vim-style navigation where appropriate (j/k for lists)
• Escape always closes/cancels

Screen Reader Considerations

• Announce dynamic content changes with aria-live
• Label all interactive elements
• Use semantic HTML (button, not div with onClick)
• Hide decorative elements from assistive tech

Anti-Patterns to Avoid

Visual

• ❌ Pure white (#fff) or pure black (#000) backgrounds
• ❌ Default system fonts (Arial, Times New Roman)
• ❌ Overly saturated colors
• ❌ Drop shadows that look like Figma defaults
• ❌ Border radius inconsistency (mixing 4px, 8px, 12px randomly)
• ❌ Text directly on images without overlay

Interaction

• ❌ Hover effects that feel disconnected from click effects
• ❌ Animations longer than 300ms for small elements
• ❌ Loading spinners for operations under 300ms
• ❌ Focus outlines that are removed entirely
• ❌ Click targets smaller than 44px on touch devices

Content

• ❌ "No data" as an empty state
• ❌ Technical error messages ("Error 500")
• ❌ Lorem ipsum in production
• ❌ Generic placeholder images

Polish Checklist

Before considering a component/page complete:

• [ ] All interactive elements have hover, focus, active states
• [ ] Tab navigation works logically
• [ ] Empty state is designed and implemented
• [ ] Loading state shows content shape (skeleton)
• [ ] Error states provide helpful recovery guidance
• [ ] Dark mode works and isn't just inverted
• [ ] Animations respect prefers-reduced-motion
• [ ] Touch targets are minimum 44px
• [ ] Colors meet WCAG AA contrast ratios
• [ ] Typography hierarchy is clear without color
• [ ] Component works at 200% browser zoom

Reference

For detailed micro-interaction patterns, animation recipes, and delight techniques, see references/delight-catalog.md.